Exhaust conduit

ABSTRACT

The invention concerns an exhaust conduit ( 1 ) comprising an outer tube ( 3 ) and an inner tube ( 2 ) positioned inside the outer tube ( 3 ) so as to delimit, between those two tubes ( 2, 3 ), a peripheral volume ( 4 ) inside which is implanted a material ( 5 ) for thermal insulation of said conduit ( 1 ) and at one first end ( 6 ) of said conduit ( 1 ), first means ( 8 ) for connection to a first exhaust element and at a second end ( 7 ) of said conduit ( 1 ), second means ( 9 ) for connecting said pipe ( 1 ) to a second exhaust element comprised in said exhaust line. Said conduit ( 1 ) is characterized in that it comprises, proximate its second end ( 7 ), means ( 10 ) for preventing exhaust gases circulating inside the inner tube ( 2 ) from penetrating into the peripheral volume ( 4 ) delimited by said inner tube ( 2 ) and the outer tube ( 3 ).

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to an exhaust conduit, which an exhaust line of an internal combustion engine includes.

This invention relates to the field of the car industry, and more particularly to that of the manufacture of the equipment ensuring the exhaust of gases resulting from the combustion of a fuel by a thermal internal combustion engine.

In this respect, it should be noted that such an engine is supplemented with an exhaust line comprising at least one exhaust conduit, for example consisting of an exhaust downtake connected, on the one hand, to the engine through a collector and, on the other hand, to a silencer and/or a gas-decontaminating element, such as a particle filter.

It is in particular inside such an exhaust downtake that circulate the exhaust gases, which, because of the proximity of the engine, have a particularly high temperature.

Now, such an exhaust downtake passes proximate elements and organs (filters, hose connections, . . . ), namely located in the motor compartment, likely to undergo degradations under the action of high temperature and the protection of which should be ensured.

Such an exhaust downtake can also be connected to a decontaminating element (catalyst, particle filter, . . . ), located downstream of this exhaust downtake, and the operation of which is optimal for exhaust gases at high temperature, so that these gases should be maintained at high temperature until their arrival in the said decontaminating element.

(2) Description of the Prior Art

To this end, there has been devised an exhaust downtake comprising two tubes, an external tube and an internal tube. This internal tube is positioned inside the external tube, so as to delimit between these two tubes a peripheral volume inside which is implanted a material for the heat insulation of the exhaust downtake.

In such an embodiment, the peripheral volume receiving the insulating material communicates, at the level of its one end, with the internal volume of the internal tube inside which the exhaust gases circulate. These gases are then likely to penetrate into the peripheral volume and to be in contact with the insulating material, which must then being chosen so as to have a good resistance to these gases and high temperatures, in order to avoid any degradation. In this respect, it should be noted that an insulating material having such performances is particularly expensive, which considerably increases the cost of such an exhaust downtake.

In addition and in order to define a peripheral volume likely to accommodate an insulating material, the external tube must be positioned adequately with respect to the internal tube, which is ensured through indentations provided for at the level of this internal tube or (and preferably) of this external tube and which rest on this external tube or this internal tube, respectively.

Such indentations adopt, for example, the shape of punches and have drawbacks consisting, on the one hand, in causing an embrittlement of the exhaust downtake and, on the other hand, in creating a thermal bridge between the internal and external tubes resulting into bad performances in term of insulation, even a total absence of insulation, of the exhaust downtake.

SUMMARY OF THE INVENTION

The present invention pretends to be capable of coping with the drawbacks of the exhaust conduits of the state of the art.

To this end, the invention relates to an exhaust conduit, which an exhaust line of an internal combustion engine comprises, and which includes, on the one hand, an external tube and an internal tube positioned inside the external tube so as to delimit, between these two tubes, a peripheral volume inside which is implanted a material for heat insulation of this conduit, on the other hand and at the level of a first end of this exhaust conduit, first means for connecting this exhaust conduit to a first exhaust element, in particular an exhaust-gas collector and, in addition and at the level of a second end of this exhaust conduit, second means for connecting this conduit to a second exhaust element, which said exhaust line comprises. This exhaust conduit is characterized in that it includes, proximate its second end, means for preventing a penetration of the exhaust gases, circulating inside the internal tube, into the peripheral volume delimited by this internal tube and the external tube.

Another feature consists in that the means for preventing a penetration of gases into the peripheral volume consist of a ring inserted over the internal tube and over which is positioned the external tube and/or the second connecting means.

According to an additional feature, the second connecting means is, on the one hand, positioned over said ring and, on the other hand, slid inside or over the external tube, which this second connecting means is made integral with, namely through welding.

Still another feature relates to the fact that the ring is inserted over the internal tube with the possibility of displacement with respect to this internal tube and/or to the external tube and/or to the second connecting means, while the conduit includes means for maintaining the ring inserted onto this internal tube.

In fact, the means for maintaining the ring on the internal tube are formed of a shoulder which includes, internally, the second connecting means and which cooperates with this ring.

According to an additional feature, the ring is made out of a metallic material and, in particular, consists of a mesh wire. However, this ring can also be made out of a heat-insulating material, in particular a fiber-based material having a high thermal resistance.

Another feature consists in that the internal and external tubes are made integral at the level of the first connecting means, namely through welding.

The invention also relates to an exhaust downtake, which includes an exhaust line of an internal combustion engine and which includes or consists of an exhaust conduit as described above.

Finally, the invention relates to an exhaust line of an internal combustion engine including an exhaust conduit as described above.

The advantages of this invention consist in that the conduit includes means for preventing a penetration of the gases into the peripheral volume, which impedes these gases from entering into contact with the insulating material, which then does not suffer any degradation.

This authorizes the use of an insulating material, which, since it is protected from the exhaust gases, can have a substantially lower mechanical strength than the insulating material used in the state of the art and, therefore, has a substantially lower cost than the insulating material of the state of the art.

Another advantage consists in that, on the one hand, the internal and external tubes are made integral at the level of the first connecting means and, on the other hand, the means for preventing a penetration of the gases into the peripheral volume consist of a ring, implanted at the level of the second end of the conduit, inserted over the internal tube and over which is positioned the external tube and/or the second connecting means, this with the possibility of displacement of this ring. Such an embodiment authorizes, on the one hand, a relative movement of the internal tube with respect to the external tube, due to phenomena of differential thermal dilation and, on the other hand, an adequate positioning of this internal tube with respect to the external tube and the second connecting means, this by avoiding the above-mentioned drawbacks related to the indentations and by adequately delimiting the peripheral volume.

Other goals and advantages of this invention will clearly appear from the following description relating to embodiments, which are given only by way of indicative and non-restrictive examples.

This description will be better understood when referring to the attached drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an exhaust conduit according to the present invention;

FIG. 2 is a schematic detail view of the second end of the exhaust conduit shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to the field of the car industry, and more particularly to that of the manufacture of the equipment ensuring the exhaust of gases resulting from the combustion of a fuel by a thermal internal combustion engine.

As can be seen in the attached figures, the invention relates to an exhaust conduit 1, which an exhaust line of an internal combustion engine includes. In this respect, it should be noted that such an exhaust conduit 1 is, preferably, comprised of an exhaust downtake, knowing that the present invention is however in no way limited to it.

Such an exhaust conduit 1 includes an internal tube 2 inside which the exhaust gases circulate. This internal tube 2 can be made of one single part, but is preferably made from two half shells that are united, in particular through welding, which advantageously allows providing such a tube 2 with a complex shape, adapted to its environment, namely inside a motor compartment.

This exhaust conduit 1 also includes an external tube 3 inside which said internal tube is implanted 2, this external tube 3 being made, preferably, from two half shells united to each other, in particular through welding, this over said internal tube 2. Such an assembly of half shells allows, here too, providing this external tube 3 with a complex shape and easily and suitably positioning the internal tube 2 inside this external tube 3.

In this respect, it should be noted that the positioning of the internal tube 2 inside the external tube 3 is carried out so as to delimit, between these two tubes 2, 3, a peripheral volume 4 inside which is implanted a material 5 designed capable of ensuring a heat insulation of the exhaust conduit 1.

Such an insulation allows, on the one hand, protecting the surroundings of the exhaust conduit 1 from the high exhaust-gas temperature and, on the other hand, maintaining the gases at high temperature at the exit of the conduit 1, so as to allow the optimal operation of the decontaminating means located downstream of this conduit 1.

As can be seen in FIG. 1, this exhaust conduit 1 has two ends 6, 7, a first end 6 of which located upstream of the conduit 1 as well as a second end 7 located downstream of this conduit 1, this according to the direction of circulation of the gases in this conduit 1.

This conduit 1 then includes, at the level of this first end 6, first means 8 for connecting this exhaust conduit 1 to a first exhaust element (not shown) and which, in the case of an exhaust conduit 1 defined by an exhaust downtake, consists of an exhaust-gas collector.

It should be noted that it is, in particular, at the level of this first connecting means 8 that the internal 2 and external 3 tubes are made integral one 2 with the other 3, in particular through welding.

In this respect, such a first connecting means 8 preferably consists of a flange or the like.

This conduit 1 also includes, and at the level of said second end 7, second means 9 for connecting this exhaust conduit 1 to a second exhaust element (not shown), which, in the case of an exhaust conduit 1 defined by an exhaust downtake, consists of a silencer or a decontaminating element, in particular a particle filter.

In fact, this second connecting means 9 can consist of a part allowing ensuring the connection between a second exhaust element and either the internal tube 2 or the external tube 3, even these two tubes 2, 3.

As can be seen in FIG. 2 corresponding to a preferred embodiment of the invention, this second connecting means 9, on the one hand, allows ensuring the connection between the second exhaust element and the external tube 3 and, on the other hand, preferably consists of a binding band or the like.

According to the invention, this exhaust conduit 1 includes, proximate its second end 7, means 10 for preventing a penetration of exhaust gases, circulating inside the internal tube 2, into the peripheral volume 4 delimited by this internal tube 2 and the external tube 3.

In fact, the means 10 for preventing a penetration of gases into the peripheral volume 4 consist of a ring 11, on the one hand, inserted over the internal tube 2 and, on the other hand, over which 11 is positioned the external tube 2 and/or the second connecting means 9.

According to a first embodiment, not shown, the external tube 2 is inserted over this ring 11.

However and according to a preferred embodiment of the invention that can be seen in FIG. 2, the second connecting means 9 is inserted over said ring 11.

According to another feature of the invention, this second connecting means 9, on the one hand, is positioned over said ring 11 and, on the other hand, slid over or, and preferably (FIG. 2), inside the external tube 3, which this second connecting means 9 is made integral with, namely through welding.

It should be noted that said ring 11 is inserted over the internal tube 2, this with a possibility of displacement with respect to the internal tube 2 and/or the external tube 3 and/or the second connecting means 9.

In this respect, it should be noted that the internal tube 2 is likely to adopt a relative displacement with respect to the external tube 3, due to phenomena of thermal differential expansion. Such a relative displacement is, in particular, noticeable at the level of the second end 7 of the conduit 1, since this internal tube 2 is only made integral with the external tube 3 at the level of the first end 6 of this conduit 1.

According to a particular embodiment, this ring 11 is made integral with the internal tube 2 and is then likely to move with respect to the external tube 3 and/or the second connecting means 9.

According to another embodiment, this ring 11 can be made integral with the external tube 3 and/or the second connecting means 9, so that the internal tube 2 is likely to move with respect to this ring 11.

However and according to a preferred embodiment of the invention that can be seen in FIG. 2, the ring 11 is inserted over the internal tube 2 with a possibility of displacement with respect to this internal tube 2, with respect to the external tube 3 and with respect to the second connecting means 9.

According to an additional feature, the exhaust conduit 1 also includes means 12 for maintaining the ring 11 inserted on the internal tube 2.

Such means 12 advantageously allow maintaining the ring 11 on the internal tube 2, even during the relative displacements of this internal tube 2 with respect to the external tube 3 and the second connecting means 9.

In fact, such means 12 for maintaining the ring 11 on the internal tube 2 consist of a shoulder 13 the second connecting means 9 includes internally, and which cooperates with this ring 11.

According to another feature of the invention, the ring 11 is made out of a metallic material and consists, in particular, of a mesh wire.

However and according to another embodiment, this ring 11 can be made out of a heat-insulating material, in particular a fiber-based material having a high thermal strength, for example non-intumescent fibers of the type of those described in patent application EP 906495.

In this respect, it should be noted that the use of means 10 for impeding a penetration of the exhaust gases into the peripheral volume 4 advantageously allows avoids arranging, inside this peripheral volume 4 and along the whole exhaust conduit 1, an insulating material 5 particularly resistant to the hot exhaust gases and, hence, particularly expensive. Such an insulating material can, for example, be reserved only for the manufacture of a ring 11, whereas the insulating material arranged in the peripheral volume 4, this along the whole exhaust conduit 1, except at the level of its second end 7, can consist of fibers having a lower mechanical strength and considerably cheaper.

The use of these fibers can also be contemplated with a ring 11 made out of a metallic material such as mentioned above.

The invention also relates to an exhaust downtake, which an exhaust line of an internal combustion engine includes and which includes or consists of an exhaust conduit 1 as described above.

Finally, the invention relates to an exhaust line of an internal combustion engine including an exhaust conduit 1 as described above.

Although the invention has been described in connection with a particular embodiment, it is clearly understood that it is in no way limited to it and that various changes of shape, material and combinations of these various elements can be made, without departing from the scope and the spirit of the invention. 

1. Exhaust conduit, which an exhaust line of an internal combustion engine comprises, and which includes, on the one hand, an external tube and an internal tube positioned inside the external tube so as to delimit, between these two tubes, a peripheral volume inside which is implanted a material for heat insulation of this conduit, on the other hand and at the level of a first end of this exhaust conduit, first means for connecting this exhaust conduit to a first exhaust element, in particular an exhaust-gas collector and, in addition and at the level of a second end of this exhaust conduit, second means for connecting this conduit to a second exhaust element, which said exhaust line comprises, characterized in that it includes, proximate its second end, means for preventing a penetration of the exhaust gases, circulating inside the internal tube, into the peripheral volume delimited by this internal tube and the external tube.
 2. Exhaust conduit according to claim 1, wherein the means for preventing a penetration of the gases into the peripheral volume consist of a ring inserted over the internal tube and over which is positioned the external tube and/or the second connecting means.
 3. Exhaust conduit according to claim 2, wherein the second connecting means is, on the one hand, positioned over said ring and, on the other hand, slid inside or over the external tube, which this second connecting means is made integral with, namely through welding.
 4. Exhaust conduit according to claim 2, wherein the ring is inserted over the internal tube with a possibility of displacement with respect to the internal tube and/or the external tube and/or the second connecting means, while the exhaust conduit includes means for maintaining the ring inserted on this internal tube.
 5. Exhaust conduit according to claim 4, wherein the means for maintaining the ring on the internal tube consist of a shoulder the second connecting means includes internally, and which cooperates with this ring.
 6. Exhaust conduit according to claim 2, wherein the ring is made out of a metallic material and consists, in particular, of a mesh wire.
 7. Exhaust conduit according to claim 2, wherein this ring is made out of a heat-insulating material, in particular a fiber-based material having a high thermal strength.
 8. Exhaust conduit according to claim 1, wherein the internal and external tubes are made integral at the level of the first connecting means, namely by welding.
 9. Exhaust conduit according to claim 1, wherein the first connecting means consists of a flange, namely for connection to an exhaust-gas collector.
 10. Exhaust conduit according to claim 1, wherein the second connecting means consists of a binding band or the like.
 11. Exhaust downtake, which an exhaust line of internal combustion engine includes, and which includes or consists of an exhaust conduit according to claim
 1. 12. Exhaust line of an internal combustion engine and which includes an exhaust conduit according to claim
 1. 